From: Paolo Bonzini <pbonzini@redhat.com>
To: "Wangting (Kathy)" <kathy.wangting@huawei.com>
Cc: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [question] the patch which affect performance of virtio-scsi
Date: Tue, 03 Feb 2015 09:42:03 +0100 [thread overview]
Message-ID: <54D089DB.1040009@redhat.com> (raw)
In-Reply-To: <54D032FB.404@huawei.com>
On 03/02/2015 03:31, Wangting (Kathy) wrote:
> Hi Paolo,
>
> Recently I test IO performance with virtio-scsi, and find out that the patch of
> "virtio-scsi: add support for the any_layout feature" affects IO performance of model
> with 4KB 32iodepth sequence read.
>
> Why cdb and sense is removed from the struct of VirtIOSCSICmdReq and VirtIOSCSICmdResp?
Because I could not find any other way to implement ANY_LAYOUT, and
virtio 1.0 requires that feature.
The performance however was already improved in commit faf1e1f
(virtio-scsi: Optimize virtio_scsi_init_req, 2014-09-16).
Paolo
> How do you consider the impact of the changes to the performance?
> Although the latest version of qemu can optimize the performance by the way of reading merger,
> I think the affect of this patch cannot be ignored.
prev parent reply other threads:[~2015-02-03 8:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-03 2:31 [Qemu-devel] [question] the patch which affect performance of virtio-scsi Wangting (Kathy)
2015-02-03 2:56 ` Wangting (Kathy)
2015-02-03 8:49 ` Paolo Bonzini
2015-02-07 11:26 ` Wangting (Kathy)
2015-02-08 10:10 ` Paolo Bonzini
2015-02-09 2:53 ` Wangting (Kathy)
2015-02-03 8:42 ` Paolo Bonzini [this message]
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